This was mentioned in #835, but is a new issue altogether

Expected Results: Broken chest, broken dreams.

Results: Item duplication up to a stack at a time.

Method:

1. Acquire an alchemical chest, a friend (or autonomous activator) and 2 of the items you need to duplicate.
2. Place chest, insert 1 of the to be duplicated item.
3. Get the friend (or activator friend) to break the chest while you have the chest's GUI open.
4. Scroll wheel the item into your inventory from the chest, it will gain an increasing large negative EMC value, and the stack in your inventory will increase until it maxes the stack.
5. For extra laughs, manually move the negative EMC item to your inventory, it will become a version of the item with 0 EMC when the gui is closed.

Tried to replicate this error in build 507, the item in the chest dropped to zero, did not go into negatives, so kinda almost fixed?

To confirm, and since I don't want to set up a manual test environment again, it still duplicates the item though, correct?

Correct. It was still there. With the latest commits from Virtuoel and pahimar, it seemingly is fixed. You can no longer remove the item once the chest has been destroyed, and cannot scrollwheel the item into your inventory.

Confirmed fixed via Virtuoel PR